How to open .3DM files (Rhino 3D models) on Android, Windows and Linux

An architect, a jewellery designer or a product engineer sends you a .3dm file, and nothing on your computer or phone opens it. That’s because it’s the native file of Rhino, a professional 3D modelling program most people don’t own.

The short answer: to see a .3dm file as it is, you need Rhino or a free tool that reads Rhino’s format, and the easiest route on a phone is to ask for an OBJ, STL, 3MF or glTF copy. Folders recognises .3dm files, but its offline 3D viewer can’t draw Rhino geometry yet. It does open those exported copies fully.

What is a .3DM file?

3DM is the file format of Rhinoceros (Rhino), made by Robert McNeel & Associates. McNeel publishes a free toolkit called openNURBS that lets other programs read and write it, which is how the free options below can open it.

Rhino is a NURBS modeller. Instead of building shapes from triangles, it describes curves and surfaces mathematically, so a ring or a car body stays perfectly smooth at any size. A .3dm file can hold:

• NURBS curves and surfaces, and solids made from them (polysurfaces)
• SubD and mesh objects
• layers, materials, named views, dimensions and notes
• the display meshes Rhino uses to draw the surfaces on screen
• a small preview image

That mix is why ordinary 3D viewers struggle. They understand triangles, and a NURBS surface has to be turned into triangles first. 3DM files are common in architecture, jewellery, industrial and product design, and boat building. Grasshopper, Rhino’s visual programming add-on, saves its own .gh files, which are a different thing.

Opening a .3DM file in Folders: what to expect

1. Install Folders from the download page and let it see your files.
2. Find the file, or search for .3dm, and tap it.
3. The 3D viewer shows Can’t display this model, explaining that Rhino .3dm files aren’t supported by the offline viewer and suggesting an export as OBJ, STL or glTF.
4. If another app on the device reads 3DM, tap Open with another app.

The same happens on Windows, where the installer also lists Folders in File Explorer’s Open with menu for .3dm. On Linux, Folders’ 3D viewer isn’t available yet (it needs a web view the Linux version doesn’t have), and Open with… passes the file on.

What you can do with it in Folders

• Keep it and pass it on. Rename it, move it, share it, or Compress to ZIP to send it with the rest of a project.
• Open the exported copy. Once you have an OBJ, STL, 3MF, glTF/GLB or FBX version, Folders’ 3D viewer shows it with everything it offers: turn and zoom, Wireframe, Details (meshes, triangles, size in model units), Z axis is up, Auto-rotate and Save screenshot.

Asking the sender for an export. In Rhino, File → Export Selected or File → Save As offers OBJ, STL and 3MF, and recent versions also glTF. For a jewellery or product model to look at or print, STL or 3MF is fine; for something with colours and materials, ask for GLB.

Other ways to open .3DM files

• Rhino (Windows): the original program, with a free 90-day evaluation.
• Online 3D Viewer (3dviewer.net): reads 3DM in a web browser, on a phone too, and can export the model as OBJ, STL or GLB for Folders.
• Blender (free) with the import_3dm add-on, which brings Rhino files in as meshes.

Problems opening a .3DM file?

A viewer outside Rhino shows nothing, or only some objects. Many viewers draw the display meshes Rhino stores in the file rather than the surfaces themselves. If the file was saved with Rhino’s Save Small option, those meshes were left out. Ask for a normal save or an export.

The export looks faceted. Smooth NURBS surfaces become triangles on export, and the default mesh settings can be coarse. Ask for a finer mesh in Rhino’s export options.

Rhino says the file comes from a newer version. Each Rhino version opens older files but not newer ones. The sender can use Save As and choose an older version.

You were sent a .gh file. That’s a Grasshopper definition, a recipe that builds geometry inside Rhino, not a model. Ask for the result saved as .3dm, or exported.

Questions people ask

Can I open a 3DM file without Rhino? Yes. Online 3D Viewer and Blender (with the import_3dm add-on) both read it for free. Folders can’t draw it yet, but it opens the exported OBJ, STL, 3MF or glTF.

Can I open a 3DM file on Android? Online 3D Viewer works in a phone’s web browser. For an offline look, get an exported copy and open it in Folders.

How do I convert 3DM to STL or OBJ? In Rhino, use File → Export Selected. Without Rhino, load the file into Online 3D Viewer and use its export.

3DM vs STEP: what’s the difference? Both keep exact curved surfaces. 3DM is Rhino’s own format, with layers and materials; STEP is a neutral standard for passing CAD data between programs. Neither opens in Folders, but both can be exported to STL or OBJ, which do.

Related guides: STL, OBJ and 3MF files and GLB and glTF files. See all 382 file types Folders opens.